Sums the values of an assigned quantity from the point till the outlet. The final result is then a matrix of values containing the sum of the quantity in input on all upriver points: 
<table>
<tr>
<td>
   S=sum<sub>ij</sub> A<sub>j</sub>
</td>
</tr>
</table>
where <i>i</i> is the point examined and the index <i>j</i> varies on all points upriver with respect to the point examined.
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<h3>Inputs</h3>
<ul>      
<li>the file containing the drainage directions (obtained with FlowDirections or DrainDir)</li>
<li>the file containing the quantity to sum</li>
</ul>
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<h3>Output</h3>
<ul>      
<li>the file containing the summed quantities downstream</li>
</ul>